Surface Waves in a Floating Magnetic Fluid Layer under Vertically Oscillating Magnetic Field

Purpose. Standing waves arising in a magnetic fluid layer in the presence of a vertically oscillating magnetic field were investigated experimentally. This paper is a continuation of our previous work aimed to study the free surface deformation of a magnetic fluid layer lying on a liquid substrate in a vertically oscillating spatially uniform magnetic field.  Metods. The research method was based on a standard experimental setup consisting of Helmholtz coils powered by alternating current. It was used to study the stability of a two-layer system of liquids in an alternating vertical field. To effectively process the results of the experiments, the optical part of the experimental setup was modernized, for which the surface of the liquid under study was illuminated by an LED circular light source. To process the profiles of the surface of the magnetic fluid obtained during the experiment, based on GNU Octave, an author's algorithm was developed that allows determining the length of the generated waves. 

Results. The results of an experiment with different thicknesses of magnetic fluid layers in cuvettes of different diameters are presented, processed, and generalized. It is shown that the length of the emerging standing wave decreases with increasing frequency of the alternating magnetic field, increases with increasing cell diameter, and does not depend on the thickness of the MF layer. The wave number of standing waves increases monotonically with the growth of the dimensionless frequency of magnetic field oscillations. All the parameters and dependences considered in the problem are valid for the case of deep water. 

Conclusion. As a conclusion, we note that the results obtained in the course of the experiment expand the understanding of the behavior of multiphase systems with a ferrofluid in a magnetic field.

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